Apparatus for making a random access to the reverse common channel of a base station in CDMA and method therefor

ABSTRACT

An apparatus for making a plurality of terminals have a random access to the reverse common channel system in CDMA, comprises code synchronization detection information broadcast means provided in the base station for broadcasting the state information of a channel card in real time for the terminals to recognize the code synchronization detection when the code synchronization of a certain data is acquired through performing the code synchronization of the preambles transmitted from the terminals through the reverse common channel, and data transmission determination, means provided in the terminals for making the terminals to have attempted data transmission in the same time slot with the data of the code synchronization detection continuously transmit data and the other terminals stop data transmission.

NOTE: More than one reissue application has been filed for the reissueof U.S. Pat. No. 6,614,771. The reissue applications are applicationSer. Nos. 11/218,277, filed Sep. 2, 2005 (the present application), and11/951,939, filed Dec. 6, 2007, which is a continuation reissueapplication of Ser. No. 11/218,277 and is still pending.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention concerns an apparatus for making a plurality ofcellular phones randomly access a common channel to transmit data inCDMA (Code Division Multiple Access), and a method therefor.

2. Technical Background

Recently, it has been demanded that the mobile communication system mayprovide data communication services to enable exchanges of moving imageand character data together with those of conventional voicedinformation during movement IMT-2000 (International MobileTelecommunication-2000) is an international project to develop a mobilecommunication system to enable such data communication services based onan internationally integrated standard. In addition, an effort has beenmade to achieve high speed data transmission with some limitation in themobile characteristics, and particularly, the wireless LAN proposed inIEEE 802.11 standard is commercially able to make data transmission at 2Mbps (Mega bit per sec).

Generally, the circuit-switch, which is employed in the present publicswitched telephone network (PSTN), digital cellular system and personalcommunication system, is not desirable to make such high speed datatransmission because of ineffectively using a limited number ofchannels. In order to resolve the disadvantages of the circuit-switch,the packet-switch has been proposed to make high speed data transmissionin IMT-2000, which is under development for LAN or the standard of thefuture mobile communication system. The band spread method of CDMAapplied to the present digital cellular system has a large communicationcapacity, and is prevented from external tapping and stabilized to makecommunications under the multipath environment generated by the radiochannels rapidly changed through movement, so that it is widely used inthe commercial wireless LAN, CDMA One of LMNQ (Lucent Motorola, Nortel,Qualcomm, Samsung) proposed as the standard of the future IMT-2000, orW-CDMA (Wideband-CDMA) chiefly developed in Europe and Japan.

The future IMT-2000 system is to support both voiced data and packetdata communications. In this case, it is very ineffective that thepacket data is assigned with an exclusive channel as the voiced data.Namely, although the continuous voiced data must be assigned with anexclusive channel, it is desirable for effective use of resources andsimplification of the system that the discontinuous small packet dataare transmitted through the reverse common channels less than the numberof the active terminals. Moreover, if the number of the subscribers isincreased, and thus the amount of the data transmitted, the reversecommon channels must be necessarily used for the effective use ofresources.

The ALOHA method is the most effective way of channel access and datatransmission through the reverse common channel, and a typical randomaccess, which is developed by Hawaii University in 1970 as a protocolfor the wireless network between the islands of Hawaii State. However,such ALOHA suffers the inefficiency of data transmission performedwithout any timed schedule between the base station and terminals, andnetwork overloaded due to frequent collision of data transmitted by anumber of terminals. The slotted ALOHA has been developed to define astandard time between the base station and terminal in order to copewith such problems. This method is to allow the data transmission of aterminal only in a set time, so that the rate of substantial data andthus the transmission efficiency is increased, and the interferencesfrom another terminal is reduced, thereby improving the efficiency ofthe whole network. However, since the slotted ALOHA makes the datatransmission basically in the contention mode, it is impossible to avoidcollisions of data transmitted from the terminals. Hence, if there is anadditional channel for controlling and transmitting information in theforward link from the base station to the terminals, the base stationbroadcasts the information of the received data to the terminals inorder to avoid such data collision.

In the ALOHA system employing CDMA, each terminal uses a different codeor the same code with a time offset to avoid data collision. Inaddition, a preamble signal is firstly transmitted to determine thepower to be used for data transmission, and the initial synchronizationwith the code to use and the tracking of the code synchronization isperformed previous to the data transmission, thereby preventing datatransmission error. Describing the conventional ALOHA protocol employingCDMA in reference to FIG. 1, a terminal makes an access attempt totransmit data. The access attempt consists of a plurality of accesssub-attempts, each of which in turn consists of a plurality of accessprobe sequences, each of which in turn consists of a plurality of accessprobes. The access probe consists of a preamble transmitting a pilotchannel without any substantial information to evaluate the channelsituation and to make the initial synchronization between the codes ofthe terminal and base station and the tracking of the codesynchronization, and an access channel message capsule containing theaccess information or the user's data following the preamble. In orderto transmit an access signal or data through the reverse common channel,a terminal firstly transmits an access probe at a given power level,which must have a minimum value to reduce the interferences affectingthe other terminals that transmit data through an exclusive channel orother reverse common channels. Then, the terminal which made an attemptto transmit data with the first access probe waits for a prescribed timeinterval TA the signal from the base station representing whether thetransmitted data is received. If the first access probe fails to reachthe base station, the terminal makes another attempt to retransmit thesecond probe at a power level increased by a given level PI compared tothe power level of the first probe after a random time interval RT. Ifnot succeeding in the data transmission through a prescribed number ofthe access probes of the first access probe sequence, the terminalperforms the second access probe sequence after passing an additionalrandom time interval RS.

While the conventional ALOHA protocol system employing CDMA can make astable data transmission in the reverse common channel by performingstably the code synchronization and the tracking thereof with thepreamble of a sufficient length even when many data are transmittedthrough the reverse common channel, the preamble is the signal toestablish the code synchronization, and less important and longer thanthe substantial data. Thus, if the synchronization is exactly acquiredin the preamble but with an error in transmission of the substantialdata, the preamble should be retransmitted reducing the datatransmission efficiency.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an apparatus formaking a plurality of cellular phones randomly access a common channelto transmit data in CDMA, which enables the base station to broadcast asignal representing whether it has acquired the synchronization signalof the data received through the reverse common channel or no, so as toprevent the terminals from unnecessarily transmitting data, therebyavoiding interference signals generated in the reverse common channel.

It is another object of the present invention to reduce the power usedin the terminal to employ an exclusive channel or the reverse commonchannel to transmit data, and to enable the failed terminal to quicklyretransmit data.

It is still another object of the present invention to provide anapparatus for making a plurality of cellular phones randomly access acommon channel to transmit data in CDMA, which may stably perform thecode synchronization and the tracking thereof with a preamble of thesame length, and achieve reliable data transmission, and reduce the timetaken for transmitting data.

It is further another object of the present invention to enable the basestation to broadcast the information concerning the state of the channelcard to all terminals in real time so as to prevent the terminals fromunnecessarily transmitting data.

According to the present invention, an apparatus for making a pluralityof terminals have a random access to the reverse common channel of abase station in CDMA, comprises code synchronization detectioninformation broadcast means provided in the base station forbroadcasting the state information of a channel card in real time forthe terminals to recognize the code synchronization detection when thecode synchronization of a certain data is acquired through performingthe code synchronization of the preambles transmitted from the terminalsthrough the reverse common channel, and data transmission determinationmeans provided in the terminals for making the terminals to haveattempted data transmission in the same time slot with the data of thecode synchronization detection continue data transmission and the otherterminals stop data transmission.

According to an aspect of the present invention, each of the terminalscomprises a data generator for generating the data transmitted to thebase station, a data transmitter for transmitting the data generatedfrom the data generator, a terminal RF signal processor for convertingthe data from the data transmitter into an RF signal transmitted to thebase station and for processing an RF signal received from the basestation, a broadcast signal receiver for receiving a broadcast signalfrom the terminal RF signal processor to determine the datatransmission, and data transmission determination circuit forcontrolling the data transmitter to determine whether to make an attemptof transmitting data or to keep on transmitting the data presently undertransmission according to the broadcast signal.

When the data transmission determination circuit receives a broadcastsignal representing the detection of the code synchronization in a timeslot from the base station, it holds the data transmission untilreceiving a broadcast signal representing the code synchronization notacquired when it does not perform data transmission or keeps ontransmitting data when it has attempted the data transmission in thetime slot corresponding to the broadcast signal or stops the datatransmission performed in the time slot not corresponding to thebroadcast signal and holds it until receiving a broadcast signalrepresenting the code synchronization not acquired.

Preferably, the data transmission determination circuit determines thedata transmission by receiving the broadcast signal representing thedetection of the code synchronization in a time slot from the basestation, the data transmission being determined by the first or secondbroadcast signal according as the ratio of the packet length to the slotlength is 2 or 4.

The data transmitter is preferably designed to have a transmitted dataunit consisting of the preamble and user's data, and the power of thepreamble is set different from that of the user's data. The datatransmitter performs the power control according to the power controlbit transmitted after receiving the broadcast signal representing thedetection of the received signal synchronization from the base station,and maintains a constant power level regardless of the power control bittransmitted upon receiving the broadcast signal representing thereceived signal synchronization not acquired from the base station.

The base station preferably comprises a base station RF signal processorfor receiving the RF signal transmitted from the terminal, a datatransceiver for demodulating the signal from the base station RF signalprocessor to deliver it to an upper hierarchy or another network or viceversa, the data transceiver generating a signal representing whether thereceived signal synchronization is acquired or no, a detectiondetermination circuit for receiving the resultant signal of the codesynchronization used to determine whether the received signal isacquired or no upon completing the preamble of the data transmitted fromthe data transceiver, a broadcast determination circuit for determiningthe information to broadcast to the terminals according to the detectionof the received signal synchronization recognized by the detectiondetermination circuit, and a broadcast transmitter for controlling thebase station RF signal processor to transmit the broadcast signaldetermined by the broadcast determination circuit at a prescribed powerlevel in a prescribed time.

Preferably, the detection determination circuit determines the initialcode synchronization and the tracking of the synchronization in a giventime before completion of preamble transmission to make the terminalsperform the precise operation in the beginning of the slot. In addition,the detection determination circuit searches the codes around thebeginning of each time slot for a duration that may vary from the lengthof the time slot to the length of the preamble.

The broadcast determination circuit determines the broadcast signal onlywith a single bit representing the detection of the synchronization inthe preamble. The broadcast transmitter transmits the broadcast signaldetermined by the broadcast determination circuit through an additionalchannel using a different code other than the presently used code atevery time of completing the slot. Besides, the broadcast transmittertransmits the broadcast signal determined by the broadcast determinationcircuit at every time of completing the slot in the punctured formhaving the power control bit transmitted through the pilot channel and atime offset.

The present invention will now described more specifically withreference to the drawings attached only by way of examples.

BRIEF DESCRIPTION OF THE ATTACHED DRAWINGS

FIG. 1 is a schematic diagram for illustrating the data transmission inALOHA system employing a common channel in conventional CDMA;

FIG. 2 illustrates a CDMA network where the inventive apparatus isapplied;

FIG. 3 is a block diagram for illustrating the base stationcommunicating with the terminal according to the inventive apparatus;

FIG. 4A is a timing diagram for illustrating the random access to thereverse common channel in the inventive apparatus; and

FIG. 4B is a timing diagram for illustrating the random access to thereverse common channel using mini time slots in the inventive apparatus.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to FIG. 2, the subscriber's terminal 110 transmits a preamblethrough the reverse common channel to the base station, which performsthe code synchronization to receive the data generated from theterminal. CDMA network 300 controls a plurality of base stations 200,210, communicating with other networks. PSTN (Public Switched TelephoneNetwork) 400 also communicates with the CDMA network 300 to connect themobile terminal 110 with the telephone subscriber. Internet 500 alsocommunicates with the CDMA network 300 to connect the terminal 110 withthe Internet subscriber. PSDN (Public Switched Data Network) 600communicates with the CDMA network 300 to connect the terminal 110 withthe PSDN subscriber.

The base station 200 is provided with code synchronization detectioninformation broadcast means for broadcasting the state information of achannel card in real time for the terminals to recognize the codesynchronization detection when the code synchronization of a certaindata is acquired through performing the code synchronization of thepreambles transmitted from the terminals through the reverse commonchannel. In addition, each terminal 100 is provided with datatransmission determination means for making the terminals to haveattempted data transmission in the same time slot with the data of thecode synchronization detection continue data transmission and the otherterminals stop data transmission.

As shown in FIG. 3, the terminal 110 comprises a data generator 111 forgenerating the data transmitted to the base station 210, a datatransmitter 112 for transmitting the data generated from the datagenerator, a terminal RF signal processor 113 for converting the datafrom the data transmitter 112 into an RF signal transmitted to the basestation 210 and for processing an RF signal received from the basestation 210, a broadcast signal receiver 114 for receiving a broadcastsignal from the terminal RF signal processor 113 to determine the datatransmission, and data transmission determination circuit 115 forcontrolling the data transmitter 112 to determine whether to make anattempt of transmitting data or to keep on transmitting the datapresently under transmission according to the broadcast signal.

The base station 210 preferably comprises a base station RF signalprocessor 211 for receiving the RF signal transmitted from the terminal110, a data transceiver 212 for demodulating the signal from the basestation RF signal processor 211 to deliver it to an upper hierarchy oranother network or vice versa, the data transceiver 212 generating asignal representing whether the received signal synchronization isacquired or no, a detection determination circuit 213 for receiving theresultant signal of the code synchronization used to determine whetherthe received signal is acquired or no upon completing the preamble ofthe data transmitted from the data transceiver 212, a broadcastdetermination circuit 214 for determining the information to broadcastto the terminals according to the detection of the received signalsynchronization recognized by the detection determination circuit 213,and a broadcast transmitter 215 for controlling the base station RFsignal processor 211 to transmit the broadcast signal determined by thebroadcast determination circuit 214 at a prescribed power level in aprescribed time.

Describing the operation of the inventive apparatus in connection withFIGS. 3 and 4, the data generator 111 of the terminal 110 generates thedata consisting of a control signal to connect the terminal 110 with thebase station 210 and a substantial data transmitted by the user of theterminal 110. The data may be transmitted through an exclusive channelor the reverse common channel according to the traffic characteristics.In the inventive apparatus, the data is transmitted through the reversecommon channel. The data generated from the data generator is determinedto be transmitted or not according to the broadcast signal received fromthe base station 210.

The hub RF signal processor 211 of the base station 210 converts the RFsignal into the base band signal transmitted, to the data transceiver212, which performs the initial code synchronization and the trackingthereof through the preamble of the data received the reverse commonchannel. Generally speaking, while the initial code synchronization andthe tracking thereof may be determined after completing of the preamblereceiving, the probability to achieve the code synchronization may beapproximately evaluated by means of the power of the received signaleven before completion of the preamble receiving, so that the broadcastsignal may be determined prior to completion of the preambletransmission, and therefore the time taken for determining andtransmitting the broadcast signal may be reduced, thus making itpossible to broadcast in real time. Hence, the effect of broadcastingthus determined broadcast signal to all terminals prevents theinterference signals because the other terminals are stopped to transmitdata when the code synchronization has been attained.

Consequently, the base station 210 decodes the data received through thereverse common channel to make an error detection, and broadcasts thesignal representing the detection of the code synchronization of thereceived data to the terminals in real time. Namely, the detectiondetermination circuit 213 transfers the resultant signal of the codesynchronization detection of the received signal from the datatransceiver 212 after completion of the preamble to the broadcastdetermination circuit 214, which determines the preparation todemodulate the data according to the signal from the data transceiver212 representing demodulation such as the signal of the synchronizationdetection and the output signal of the detection determination circuit213.

Then, the broadcast transmitter 215 transmits the informationrepresenting the detection of the code synchronization instead of PCB(Power Control Bit) at the boundary of the ,time slot in order totransmit in real time the broadcast signal determined by the broadcastdetermination circuit 214 as transmitting PCB through the pilot channel.The possible time delay, as described above, may occur beforetransmission of the preamble, and therefore the prepared broadcastsignal is broadcast before the beginning of the time slot to prevent theperformance degradation.

The terminals 110 determines the subsequent operations depending on theinformation of the code synchronization received from the base station210. When the base station 210 transmits the signal representing thedetection of the code synchronization of the data transmitted throughthe reverse common channel in a specific time slot, the terminals thathave not transmitted data must hold until the completion of transmittingthe acquired data while the terminals that have attempted datatransmission in the corresponding time slot keep on transmitting thedata. Of course, the terminals that have attempted data transmission inthe other time slots must stop the transmission until the completion oftransmitting the acquired data.

FIG. 4A illustrates the example of attempting the data transmissionusing the beginning of the time slot determined by the system time setin the system. In this case, it is assumed that the length of thepreamble necessary for the code synchronization for the datatransmission is twice the data length. The time taken for a single datatransmission consists of a plurality of time slots. The terminal 110including the data newly generated or to be retransmitted before thebeginning of the first time slot S₀ performs the data transmission inthe first time slot interval S₀-S₁. As shown in FIG. 4A, the five dataare simultaneously transmitted, and in the next time slot interval S₁-S₂are transmitted two data through the reverse common channel to the basestation. Hence, the total of the data transmitted in the second timeslot interval is seven.

Firstly, it is assumed that the base station performs the initial codesynchronization and the tracking thereof by detecting one of the fivedata transmitted in the first time slot interval S₀-S₁. This assumptionmay be taken valid because the data are acquired different in powerlevel or transmission delay even if transmitted simultaneously accordingto the distance between the base station 200 and the terminal 110.Therefore, as shown in FIG. 4A, the detection of the data transmitted atthe beginning of the first time slot S₀ is recognized by the basestation 200 at the beginning of the third time slot S₂, transmitted toall the terminals. Then, the terminal 110 determines the next operationaccording to the broadcast signal received through the terminal RFsignal processor 113 and the broadcast signal receiver 114. Namely,receiving the broadcast signal, the terminals that have made the datatransmission at the beginning of the first time slot S₀ keep ontransmitting data, performing closed loop power control by using the PCBtransmitted from this time. Since the previous PCB is invalid due to thepreamble not acquired, the closed loop power control of the preambleprior to broadcasting the synchronization detection signal may causeabrupt change to the power generated from the terminal 110.

In the mean time, the terminals that have made data transmission at timepoints other than the beginning of the first time slot stop thetransmission to attempt retransmission in the time slot at which thenext not acquired signal is transmitted. On the other hand, if thebroadcast signal represents the synchronization not acquired, theterminal does not perform an additional operation, keeping on carryingout the operation done in the previous time slot interval. In this way,the base station may achieve more precise demodulation of the acquireddata in the reduced signal interference, transmitting data in theincreased power without degradation of the overall system performance.Namely, the data acquired from the preamble may be stably demodulated,so that the time taken for the transmission is reduced and thetransmission efficiency is improved.

FIG. 4B illustrates the data transmission procedure where the length ofthe time slot is more reduced. The length of the preamble for the codesynchronization is twice the data length as in FIG. 4A. In this case,each time slot is divided into a plurality of smaller time slots, sothat the number of the terminals 110 is reduced for a time slot. A datais transmitted in the beginning of the first time slot S₀₋₀, and twodata in the beginning of the next time slot S₀₋₁, so that the amount ofthe data transmitted at the beginning of each time slot is reduced, thusincreasing the probability of detecting in the preamble compared to thecase of FIG. 4A.

Consequently, the data transmitted in the second time slot S₀₋₁ isacquired by the base station 200 to broadcast the detection signal tothe terminal 110 in the time slot S₂₋₁ of completing the preamble.Receiving the detection signal, the terminals that have performed datatransmission in the beginning of the second time slot S₀₋₁, keep ontransmitting data while the terminals that have performed datatransmission in the other time slots stop transmission, holding untilthe time slot S₃₋₁ of receiving the signal not acquired from the basestation, and thus the terminals that have not performed datatransmission. Compared to FIG. 4A where two of seven terminals stoptransmission, the five terminals stop data transmission, and thereforeit will be noted that the reduced slot secures the stable datatransmission with reduced signal interference. Thus, the reduced slotlength reduces the probability of transmitting data in the same timeslot, so that there is increased the nubmer of the terminals stoppingunnecessary transmission after detection of the preamble. This increasesthe stability of data transmission, decreasing the signal interferencein the terminals using the exclusive channel or other reverse commonchannels. However, since the signal broadcast from the base station 200to the terminal 110 is determined by the signal received from theterminal, it is required that the slot length is maintained over aprescribed level to minimize the disadvantages caused by thetransmission delay or multi-path. Namely, if the slot length is reducedbelow the prescribed level to reduce the level of the interferencesignal, the performance of the overall system is degraded because ofincreasing the frequency of the signal interference. Hence, it isdesirable to select the slot length that may reduce the level of thesignal interference with minimizing the disadvantages caused by thetransmission delay and multi-path.

In another aspect of the present invention, a method for making aplurality of terminals have a random access to the reverse commonchannel of a base station in CDMA, comprises the steps of broadcastingfrom the base station the state information of a channel card in realtime for the terminals to recognize the code synchronization detectionwhen the code synchronization of a certain data is acquired throughperforming the code synchronization of the preambles transmitted fromthe terminals through the reverse common channel, and making theterminals to have attempted data transmission in the same time slot withthe data of the code synchronization detection continue datatransmission and the other terminals stop data transmission.

Preferably, the step of making the terminals transmit data comprises thesteps of generating the data transmitted to the base station,transmitting the data to the base station, converting the data into anRF signal transmitted to the base station and processing a broadcast RFsignal received from the base station, receiving the converted broadcastRF signal to determine the data transmission, and determining whether tomake an attempt of transmitting data or to keep on transmitting the datapresently under transmission according to the broadcast signal.

Preferably, the step of broadcasting in the base station comprises thesteps of receiving the RF signal transmitted from the terminal,demodulating the signal from the base station RF signal processor todeliver it to an upper hierarchy or another network or vice versa, andgenerating a signal representing whether the received signalsynchronization is acquired or no, receiving the resultant signal of thecode synchronization used to determine whether the received signal isacquired or no upon completing the preamble of the data transmitted,determining the information to broadcast to the terminals according tothe detection of the received signal synchronization, and controllingthe base station to transmit the broadcast signal at a prescribed powerlevel in a prescribed time.

Describing the operation of the inventive method in connection with FIG.4, the data generator of the terminal generates the data consisting of acontrol signal to connect the terminal with the base station and asubstantial data transmitted by the user of the terminal. The datagenerated from the data generator is determined to be transmitted or notaccording to the broadcast signal received from the base station.

The hub RF signal processor of the base station converts the RF signalinto the base band signal transmitted to the data transceiver, whichperforms the initial code synchronization and the tracking thereofthrough the preamble of the data received the reverse common channel.Generally speaking, while the initial code synchronization and thetracking thereof may be determined after completing of the preamblereceiving, the probability to achieve the code synchronization may beapproximately evaluated by means of the power of the received signaleven before completion of the preamble receiving, so that the broadcastsignal may be determined prior to completion of the preambletransmission, and therefore the time taken for determining andtransmitting the broadcast signal may be reduced, thus making itpossible to broadcast in real time. Hence, the effect of broadcastingthus determined broadcast signal to all terminals prevents theinterference signals because the other terminals are stopped to transmitdata when the code synchronization has been attained.

Consequently, the base station 210 decodes the data received through thereverse common channel to make an error detection, and broadcasts thesignal representing the detection of the code synchronization of thereceived data to the terminals in real time. Namely, the detectiondetermination circuit transfers the resultant signal of the codesynchronization detection of the received signal from the datatransceiver after completion of the preamble to the broadcastdetermination circuit, which determines the preparation to demodulatethe data according to the signal from the data transceiver representingdemodulation such as the signal of the synchronization detection and theoutput signal of the detection determination circuit. Then, thebroadcast transmitter transmits the information representing thedetection of the code synchronization instead of PCB at the boundary ofthe time slot in order to transmit in real time the broadcast signaldetermined by the broadcast determination circuit as transmitting PCBthrough the pilot channel.

The terminals determine the subsequent operations depending on theinformation of the code synchronization received from the base station.When the base station transmits the signal representing the detection ofthe code synchronization of the data transmitted through the reversecommon channel in a specific time slot, the terminals that have nottransmitted data must hold until the completion of transmitting theacquired data while the terminals that have attempted data transmissionin the corresponding time slot keep on transmitting the data. Of course,the terminals that have attempted data transmission in the other timeslots must stop the transmission until the completion of transmittingthe acquired data.

FIG. 4A illustrates the example of attempting the data transmissionusing the beginning of the time slot determined by the system time setin the system. Since the preamble and data constitute a transmissiondata unit, the performance depends on the power and length of thepreamble. Hence, if the transmission data unit is greater than twice thetime slot, the inventive effect is achieved, or otherwise, the effectnot obtained. The present invention sets the time slot smaller than theconventional time slot to improve the performance. The time taken for asingle data transmission consists of a plurality of time slots. Theterminal including the data newly generated or to be retransmittedbefore the beginning of the first time slot S₀ performs the datatransmission in the first time slot interval S₀-S₁. As shown in FIG. 4A,the five data are simultaneously transmitted, and in the next time slotinterval S₁-S₂ are transmitted two data through the reverse commonchannel to the base station. Hence, the total of the data transmitted inthe second time slot interval is seven.

Firstly, it is assumed that the base station performs the initial codesynchronization and the tracking thereof by detecting one of the fivedata transmitted in the first time slot interval S₀-S₁. This assumptionmay be taken valid because the data are acquired different in powerlevel or transmission delay even if transmitted simultaneously accordingto the distance between the base station and the terminal. Therefore, asshown in FIG. 4A, the detection of the data transmitted at the beginningof the first time slot S₀ is recognized by the base station at thebeginning of the third time slot S₂, transmitted to all the terminals.Then, the terminal determines the next operation according to thebroadcast signal received through the terminal RF signal processor andthe broadcast signal receiver. Namely, receiving the broadcast signal,the terminals that have made the data transmission at the beginning ofthe first time slot S₀ keep on transmitting data, performing closed looppower control by using the PCB transmitted from this time. Since theprevious PCB is invalid due to the preamble not acquired, the closedloop power control of the preamble prior to broadcasting thesynchronization detection signal may cause abrupt change to the powergenerated from the terminal.

In the mean time, the terminals that have made data transmission at timepoints other than the beginning of the first time slot stop thetransmission to attempt retransmission in the time slot at which thenext signal not acquired is transmitted. On the other hand, if thebroadcast signal represents the synchronization not acquired, theterminal does not perform an additional operation, keeping on carryingout the operation done in the previous time slot interval. In this way,the base station may achieve more precise demodulation of the acquireddata because of reduced signal interference, transmitting data in theincreased power without degradation of the overall system performance.Namely, the data acquired from the preamble may be stably demodulated,so that the time taken for the transmission is reduced and thetransmission efficiency is improved.

FIG. 4B illustrates the data transmission procedure where the length ofthe time slot is more reduced. The length of the preamble for the codesynchronization is twice the data length as in FIG. 4A. In this case,each time slot is divided into a plurality of smaller time slots, sothat the number of the terminals is reduced for a time slot. A data istransmitted in the beginning of the first time slot S₀₋₀, and two datain the beginning of the next time slot S₀₋₁, so that the amount of thedata transmitted at the beginning of each time slot is reduced, thusincreasing the probability of detecting in the preamble compared to thecase of FIG. 4A.

Consequently, the data transmitted in the second time slot S₀₋₁ isacquired by the base station to broadcast the detection signal to theterminal in the time slot S₂₋₁ of completing the preamble. Receiving thedetection signal, the terminal that have performed data transmission inthe beginning of the second time slot S₀₋₁ keep on transmitting datawhile the terminals that have performed data transmission in the othertime slots stop transmission, holding until the time slot S₃₋₁ ofreceiving the signal not acquired from the base station, and thus theterminals that have not performed data transmission. Compared to FIG. 4Awhere two of seven terminals stop transmission, the five terminals stopdata transmission, and therefore it will be noted that the reduced slotsecures the stable data transmission with reduced signal interference.Thus, the reduced slot length reduces the probability of transmittingdata in the same time slot, so that there is increased the nubmer of theterminals stopping unnecessary transmission after detection of thepreamble. This increases the stability of data transmission, decreasingthe signal interference in the terminals using the exclusive channel orother reverse common channels. However, since the signal broadcast fromthe base station to the terminal is determined by the signal receivedfrom the terminal, it is required that the slot length is maintainedover a prescribed level to minimize the disadvantages caused by thetransmission delay or multi-path. Namely, if the slot length is reducedbelow the prescribed level to reduce the level of the interferencesignal, the performance of the overall system is degraded because ofincreasing the frequency of the signal interference. Hence, it isdesirable to select the slot length that may reduce the level of thesignal interference with minimizing the disadvantages caused by thetransmission delay and multi-path.

Thus, the base station broadcasts a signal representing the detection ofthe synchronization of the data transmitted through the reverse commonchannel to all terminals to selectively stop unnecessary datatransmission, preventing the reverse common channel from being affectedby the unnecessary signal interference. This reduces the signalinterference in the radio channel to decrease the power used by theterminal performing data transmission through the exclusive or reversecommon channel. In addition, the terminals failed in data transmissionthrough the reverse common channel may expediently performretransmission, reducing delay time. Hence, the inventive apparatus maybe properly applied to a high speed data transmission system such asIMT-2000.

1. An apparatus for making a plurality of terminals have a random accessto the reverse common channel of a base station in CDMA, comprising:code synchronization detection information broadcast means provided insaid base station for broadcasting the state information of a channelcard in real time for said terminals to recognize the codesynchronization detection when the code synchronization of a certaindata is acquired through performing the code synchronization of thepreambles transmitted from said terminals through said reverse commonchannel; and data transmission determination means provided in saidterminals for making the terminals to have attempted data transmissionin the same time slot with the data of said code synchronizationdetection continue data transmission and the other terminals stop datatransmission.
 2. An apparatus for making a plurality of terminals have arandom access to the reverse common channel system in CDMA, as definedin claim 1, wherein each of said terminals comprises: a data generatorfor generating the data transmitted to said base station; a datatransmitter for transmitting said data generated from said datagenerator; a terminal RF signal processor for converting said data fromsaid data transmitter into an RF signal transmitted to said base stationand for processing an RF signal received from said base station; abroadcast signal receiver for receiving a broadcast signal from saidterminal RF signal processor to determine the data transmission; anddata transmission determination circuit for controlling said datatransmitter to determine whether to make an attempt of transmitting dataor to keep on transmitting the data presently under transmissionaccording to said broadcast signal.
 3. An apparatus for making aplurality of terminals have a random access to the reverse commonchannel system in CDMA, as defined in claim 2, wherein, when said datatransmission determines circuit receives a broadcast signal representingthe detection of the code synchronization in a time slot from said basestation, it holds the data transmission until receiving a broadcastsignal representing the code synchronization not acquired when it doesnot perform data transmission or keeps on transmitting data when it hasattempted the data transmission in the time slot corresponding to saidbroadcast signal or stops the data transmission performed in the timeslot not corresponding to said broadcast signal and holds it untilreceiving a broadcast signal representing the code synchronization notacquired.
 4. An apparatus for making a plurality of terminals have arandom access to the reverse common channel system in CDMA, as definedin claim 3, wherein said data transmission determination circuitdetermines the data transmission by receiving the broadcast signalrepresenting the detection of the code synchronization in a time slotfrom said base station, the data transmission being determined by thefirst or second broadcast signal according as the ratio of the packetlength to the slot length is 2 or
 4. 5. An apparatus for making aplurality of terminals have a random access to the reverse commonchannel system in CDMA, as defined in claim 2, wherein said datatransmitter is designed to have a transmitted data unit consisting ofthe preamble and user's data, and the power of said preamble is setdifferent from that of said user's data.
 6. An apparatus for making aplurality of terminals have a random access to the reverse commonchannel system in CDMA, as defined in claim 2, wherein said datatransmitter performs the power control according to the power controlbit transmitted after receiving the broadcast signal representing thedetection of the received signal synchronization from said base station,and maintains a constant power level regardless of the power control bittransmitted upon receiving the broadcast signal representing thereceived signal synchronization not acquired from said base station. 7.An apparatus for making a plurality of terminals have a random access tothe reverse common channel system in CDMA, as defined in claim 1,wherein said base station comprises: a base station RF signal processorfor receiving the RF signal transmitted from the terminal; a datatransceiver for demodulating the signal from said base station RF signalprocessor to deliver it to an upper hierarchy or another network or viceversa, said data transceiver generating a signal representing whetherthe received signal synchronization is acquired or no; a detectiondetermination circuit for receiving the resultant signal of the codesynchronization used to determine whether the received signal isacquired or no upon completing the preamble of the data transmitted fromsaid data transceiver; a broadcast determination circuit for determiningthe information to broadcast to said terminals according to thedetection of the received signal synchronization recognized by saiddetection determination circuit; and a broadcast transmitter forcontrolling said base station RF signal processor to transmit thebroadcast signal determined by said broadcast determination circuit at aprescribed power level in a prescribed time.
 8. An apparatus for makinga plurality of terminals have a random access to the reverse commonchannel system in CDMA, as defined in claim 7, wherein said detectiondetermination circuit determines the initial code synchronization andthe tracking of the synchronization in a given time before completion ofa preamble transmission to make said terminals perform the preciseoperation in the beginning of the slot.
 9. An apparatus for making aplurality of terminals have a random access to the reverse commonchannel system in CDMA, as defined in claim 8, wherein said detectiondetermination circuit searches the codes around the beginning of eachtime slot for a duration that may vary from the length of the time slotto the length of the preamble.
 10. An apparatus for making a pluralityof terminals have a random access to the reverse common channel systemin CDMA, as defined in claim 7, wherein said broadcast determinationcircuit determines the broadcast signal only with a single bitrepresenting the detection of the synchronization in the preamble. 11.An apparatus for making a plurality of terminals have a random access tothe reverse common channel system in CDMA, as defined in claim 7,wherein said broadcast transmitter transmits the broadcast signaldetermined by said broadcast determination circuit through an additionalchannel using a different code other than the presently used code atevery time of completing the slot.
 12. An apparatus for making aplurality of terminals have a random access to the reverse commonchannel system in CDMA, as defined in claim 7, wherein said broadcasttransmitter transmits the broadcast signal determined by said broadcastdetermination circuit at every time of completing the slot in thepunctured form having the power control bit transmitted through thepilot channel and a time offset.
 13. An apparatus for making a pluralityof terminals have a random access to the reverse common channel systemin CDMA, as defined in claim 7, wherein said broadcast transmittertransmits the broadcast signal determined by said broadcastdetermination circuit through an additional channel using a differentcode other than the presently use code at the boundary of each timeslot.
 14. A method for making a plurality of terminals have a randomaccess to the reverse common channel of a base station in CDMA,comprising the steps of: broadcasting from said base station the stateinformation of a channel card in real time for said terminals torecognize the code synchronization detection when the codesynchronization of a certain data is acquired through performing thecode synchronization of the preambles transmitted from said terminalsthrough said reverse common channel; and making the terminals to haveattempted data transmission in the same time slot with the data of saidcode synchronization detection continue data transmission and the otherterminals stop data transmission.
 15. A method for making a plurality ofterminals have a random access to the reverse common channel system inCDMA, as defined in claim 14, wherein the step of making the terminalstransmit data comprising the steps of: generating the data transmittedto said base station; transmitting said data to said base station;converting said data into an RF signal transmitted to said base stationand processing a broadcast RF signal received from said base station;receiving the converted broadcast RF signal to determine the datatransmission; and determining whether to make an attempt of transmittingdata or to keep on transmitting the data presently under transmissionaccording to said broadcast signal.
 16. A method for making a pluralityof terminals have a random access to the reverse common channel in CDMA,as defined in claim 15, wherein the step of transmission determinationcomprises the step of holding the data transmission until receiving abroadcast signal representing the code synchronization not acquired whenit does not perform data transmission or keeps on transmitting data whenit has attempted the data transmission in the time slot corresponding tosaid broadcast signal or stops the data transmission performed in thetime slot not corresponding to said broadcast signal and holds it untilreceiving a broadcast signal representing the code synchronization notacquired, when receiving a broadcast signal representing the detectionof the code synchronization in a time slot from said base station.
 17. Amethod for making a plurality of terminals have a random access to thereverse common channel system in CDMA, as defined in claim 16, whereinthe step of transmission determination includes the further step ofdetermining the data transmission by receiving the broadcast signalrepresenting the detection of the code synchronization in a time slotfrom said base station, the data transmission being determined by thefirst or second broadcast signal according as the ratio of the packetlength to the slot length is 2 or
 4. 18. A method for making a pluralityof terminals have a random access to the reverse common channel in CDMA,as defined in claim 15, wherein the step of data transmission has atransmitted data unit consisting of the preamble and user's data, andthe power of said preamble is set different from that of said user'sdata.
 19. A method for making a plurality of terminals have a randomaccess to the reverse common channel in CDMA, as defined in claim 15,wherein the step of data transmission performs the power controlaccording to the power control bit transmitted after receiving thebroadcast signal representing the detection of the received signalsynchronization from said base station, and maintains a constant powerlevel regardless of the power control bit transmitted upon receiving thebroadcast signal representing the received signal synchronization notacquired from said base station.
 20. A method for making a plurality ofterminals have a random access to the reverse common channel in CDMA, asdefined in claim 15, wherein the step of broadcasting in said basestation comprises the steps of: receiving the RF signal transmitted fromthe terminal; demodulating the signal from said base station RF signalprocessor to deliver it to an upper hierarchy or another network or viceversa, and generating a signal representing whether the received signalsynchronization is acquired or no; receiving the resultant signal of thecode synchronization used to determine whether the received signal isacquired or no upon completing the preamble of the data transmitted;determining the information to broadcast to said terminals according tothe detection of the received signal synchronization; and controllingsaid base station to transmit the broadcast signal at a prescribed powerlevel in a prescribed time.
 21. A method for making a plurality ofterminals have a random access to the reverse common channel system inCDMA, as defined in claim 14, wherein the step of broadcasting in saidbase station comprises the steps of: receiving the RF signal transmittedfrom the terminal; demodulating the signal from said base station RFsignal processor to deliver it to an upper hierarchy or another networkor vice versa, and generating a signal representing whether the receivedsignal synchronization is acquired or no; receiving the resultant signalof the code synchronization used to determine whether the receivedsignal is acquired or no upon completing the preamble of the datatransmitted; determining the information to broadcast to said terminalsaccording to the detection of the received signal synchronization; andcontrolling said base station to transmit the broadcast signal at aprescribed power level in a prescribed time.
 22. A method for making aplurality of terminals have a random access to the reverse commonchannel system in CDMA, as defined in claim 21, wherein the step ofreceiving the resultant signal determines the initial codesynchronization and the tracking of the synchronization in a given timebefore completion of a preamble transmission to make said terminalsperform the precise operation in the beginning of the slot.
 23. A methodfor making a plurality of terminals have a random access to the reversecommon channel system in CDMA, as defined in claim 22, wherein the stepof receiving the resultant signal searches the codes around thebeginning of each time slot for a duration that may vary from the lengthof the time slot to the length of the preamble.
 24. A method for makinga plurality of terminals have a random access to the reverse commonchannel system in CDMA, as defined in claim 21, wherein the step ofdetermining the information to broadcast determines the broadcast signalonly with a single bit representing the detection of the synchronizationin the preamble.
 25. A method for making a plurality of terminals have arandom access to the reverse common channel system in CDMA, as definedin claim 21, wherein the step of controlling said base station transmitsthe broadcast signal through using a different code other than thepresently used code at every time of completing the slot.
 26. A methodfor making a plurality of terminals have a random access to the reversecommon channel system in CDMA, as defined in claim 21, wherein the stepof controlling said base station transmits the broadcast signal at everytime of completing the slot in the punctured form having the powercontrol bit transmitted through the pilot channel and a time offset. 27.A method for making a plurality of terminals have a random access to thereverse common channel system in CDMA, as defined in claim 21, whereinthe step of controlling said base station transmits the broadcast signalthrough using a different code other than the presently used code at theboundary of each time slot.
 28. An apparatus for making a plurality ofterminals have a random access to the reverse common channel of a basestation in CDMA, comprising: code synchronization detection informationbroadcast means provided in said base station for broadcasting the stateinformation of a channel card in real time for said terminals torecognize the code synchronization detection when the codesynchronization of a certain data is acquired through performing thecode synchronization of the preambles transmitted from said terminalsthrough said reverse common channel; and data transmission determinationmeans provided in said terminals for making the terminals to haveacquired the code synchronization of the transmitted preambles in saidbase station continue data transmission and the other terminals stopdata transmission, wherein said base station comprises: a data generatorfor generating the data transmitted to said base station; a datatransmitter for transmitting said data generated from said datagenerator; a terminal RF signal processor for converting said data fromsaid data transmitter into an RF signal transmitted to said base stationand for processing an RF signal received from said base station; abroadcast signal receiver for receiving a broadcast signal from saidterminal RF signal processor to determine the data transmission; anddata transmission determination circuit for controlling said datatransmitter to determine whether to make an attempt of transmitting dataor to keep on transmitting the data presently under transmissionaccording to said broadcast signal, wherein, when said data transmissiondetermination circuit receives a broadcast signal representing thedetection of the code synchronization in a time slot from said basestation, it holds the data transmission until receiving a broadcastsignal representing the code synchronization not acquired when it doesnot perform data transmission or keeps on transmitting data when it hasattempted the data transmission in the time slot corresponding to saidbroadcast signal or stops the data transmission performed in the timeslot not corresponding to said broadcast signal and holds it untilreceiving a broadcast signal representing the code synchronization notacquired.
 29. An apparatus for making a plurality of terminals have arandom access to the reverse common channel of a base station in CDMA,comprising: code synchronization detection information broadcast meansprovided in said base station for broadcasting the state information ofa channel card in real time for said terminals to recognize the codesynchronization detection when the code synchronization of a certaindata is acquired through performing the code synchronization of thepreambles transmitted from said terminals through said reverse commonchannel; and data transmission determination means provided in saidterminals for making the terminals to have acquired the codesynchronization of the transmitted preambles in said base stationcontinue data transmission and the other terminals stop datatransmission, wherein said base station comprises: a data generator forgenerating the data transmitted to said base station; a data transmitterfor transmitting said data generated from said data generator; aterminal RF signal processor for converting said data from said datatransmitter into an RF signal transmitted to said base station and forprocessing an RF signal received from said base station; a broadcastsignal receiver for receiving a broadcast signal from said terminal RFsignal processor to determine the data transmission; and datatransmission determination circuit for controlling said data transmitterto determine whether to make an attempt of transmitting data or to keepon transmitting the data presently under transmission according to saidbroadcast signal, wherein said data transmitter is designed to have atransmitted data unit consisting of the preamble and user's data, andthe power of said preamble is set different from that of said user'sdata.
 30. An apparatus for making a plurality of terminals have a randomaccess to the reverse common channel of a base station in CDMA,comprising: code synchronization detection information broadcast meansprovided in said base station for broadcasting the state information ofa channel card in real time for said terminals to recognize the codesynchronization detection when the code synchronization of a certaindata is acquired through performing the code synchronization of thepreambles transmitted from said terminals through said reverse commonchannel; and data transmission determination means provided in saidterminals for making the terminals to have acquired the codesynchronization of the transmitted preambles in said base stationcontinue data transmission and the other terminals stop datatransmission, wherein said base station comprises: a base station RFsignal processor for receiving the RF signal transmitted from theterminal; a data transceiver for demodulating the signal from said basestation RF signal processor to deliver it to an upper hierarchy oranother network or vice versa, said data transceiver generating a signalrepresenting whether the received signal synchronization is acquired orno; a detection determination circuit for receiving the resultant signalof the code synchronization used to determine whether the receivedsignal is acquired or no upon completing the preamble of the datatransmitted from said data transceiver; a broadcast determinationcircuit for determining the information to broadcast to said terminalsaccording to the detection of the received signal synchronizationrecognized by said detection determination circuit; and a broadcasttransmitter for controlling said base station RF signal processor totransmit the broadcast signal determined by said broadcast determinationcircuit at a prescribed power level in a prescribed time.
 31. A methodfor making a plurality of terminals have a random access to the reversecommon channel of a base station in CDMA, comprising the steps of:broadcasting from said base station the state information of a channelcard in real time for said terminals to recognize the codesynchronization detection when the code synchronization of a certaindata is acquired through performing the code synchronization of thepreambles transmitted from said terminals through said reverse commonchannel; and making the terminals to have acquired the codesynchronization of the transmitted preambles in said base stationcontinue data transmission and the other terminals stop datatransmission, wherein the step of making the terminals transmit datacomprising the steps of: generating the data transmitted to said basestation; transmitting said data to said base station; converting saiddata into an RF signal transmitted to said base station and processing abroadcast RF signal received from said base station; receiving theconverted broadcast RF signal to determine the data transmission; anddetermining whether to make an attempt of transmitting data or to keepon transmitting the data presently under transmission according to saidbroadcast signal, wherein the step of transmission determinationcomprises the step of holding the data transmission until receiving abroadcast signal representing the code synchronization not acquired whenit does not perform data transmission or keeps on transmitting data whenit has attempted the data transmission in the time slot corresponding tosaid broadcast signal or stops the data transmission performed in thetime slot not corresponding to said broadcast signal and holds it untilreceiving a broadcast signal representing the code synchronization notacquired, when receiving a broadcast signal representing the detectionof the code synchronization in a time slot from said base station.
 32. Amethod for making a plurality of terminals have a random access to thereverse common channel of a base station in CDMA, comprising the stepsof: broadcasting from said base station the state information of achannel card in real time for said terminals to recognize the codesynchronization detection when the code synchronization of a certaindata is acquired through performing the code synchronization of thepreambles transmitted from said terminals through said reverse commonchannel; and making the terminals to have acquired the codesynchronization of the transmitted preambles in said base stationcontinue data transmission and the other terminals stop datatransmission, wherein the step of making the terminals transmit datacomprising the steps of: generating the data transmitted to said basestation; transmitting said data to said base station; converting saiddata into an RF signal transmitted to said base station and processing abroadcast RF signal received from said base station; receiving theconverted broadcast RF signal to determine the data transmission; anddetermining whether to make an attempt of transmitting data or to keepon transmitting the data presently under transmission according to saidbroadcast signal, wherein the step of data transmission has atransmitted data unit consisting of the preamble and user's data, andthe power of said preamble is set different from that of said user'sdata.
 33. A method for making a plurality of terminals have a randomaccess to the reverse common channel of a base station in CDMA,comprising the steps of: broadcasting from said base station the stateinformation of a channel card in real time for said terminals torecognize the code synchronization detection when the codesynchronization of a certain data is acquired through performing thecode synchronization of the preambles transmitted from said terminalsthrough said reverse common channel; and making the terminals to haveacquired the code synchronization of the transmitted preambles in saidbase station continue data transmission and the other terminals stopdata transmission, wherein the step of broadcasting in said base stationcomprises the steps of: receiving the RF signal transmitted from theterminal; demodulating the signal from said base station RF signalprocessor to deliver it to an upper hierarchy or another network or viceversa, and generating a signal representing whether the received signalsynchronization is acquired or no; receiving the resultant signal of thecode synchronization used to determine whether the received signal isacquired or no upon completing the preamble of the data transmitted;determining the information to broadcast to said terminals according tothe detection of the received signal synchronization; and controllingsaid base station to transmit the broadcast signal at a prescribed powerlevel in a prescribed time.
 34. An apparatus for transmitting a datapacket to a base station in a code division multiple access (CDMA)telecommunication system wherein a plurality of terminals randomlyaccess to a reverse common channel, comprising: means for receivingstate information broadcasted from the base station, the stateinformation representing that a code synchronization of the data packetis acquired in the base station, wherein a code synchronizationdetection is performed based on a preamble of the data packettransmitted from the terminals through the reverse common channel; anddata transmission determination means for determining whether the codesynchronization of the data packet is acquired or not based on the stateinformation, allowing the terminal to transmit the data packet in thesame time slot as the data packet of which the code synchronization isacquired if the code synchronization of the data packet is acquired, andallowing the terminal to stop transmission of the data packets if thecode synchronization of the data packet is not acquired.
 35. A terminalfor transmitting a data packet to a base station in a code divisionmultiple access (CDMA) telecommunication system wherein a plurality ofterminals randomly access to a reverse common channel, comprising: adata generator for generating data packets to be transmitted to the basestation; a data transmitter for transmitting the data packets generatedin said data generator; a terminal RF signal processor for convertingthe data packets from said data transmitter into a radio frequency (.RF)signal and for processing an RF signal received from the base station; abroadcast signal receiver for receiving a broadcast signal from saidterminal RF signal processor, the broadcast signal representing that acode synchronization of the data packet is acquired in the base station,wherein a code synchronization detection is performed based on apreamble of the data packet transmitted from the terminals through thereverse common channel; and data transmission determination circuit fordetermining whether the code synchronization of the data packet isacquired or not based on the broadcast signal, allowing the datatransmitter to continue to transmit the data packet if the codesynchronization of the data packet is acquired, and allowing the datatransmitter to stop transmission of the data packets if the codesynchronization of the data packet is not acquired.
 36. The terminal asrecited in claim 35, wherein the data transmitter is designed to have atransmitted data unit consisting of the preamble and user's data, andthe power of the preamble is set different from that of the user's data.37. A base station for making a plurality of terminals have a randomaccess to a reverse common channel in a code division multiple access(CDMA) system, comprising: a base station RF signal processor forreceiving an RF signal transmitted from the terminal; a data transceiverfor demodulating the RF signal from said base station RF signalprocessor and generating a data packet to deliver it to an upperhierarchy or another network or vice versa, generating a signalrepresenting whether a code synchronization of the data packet isacquired or not, a detection determination means, determining whetherthe data packet is acquired or not upon completing a preamble of thedata packet; a broadcast determination means for determining informationrepresenting that the code synchronization of the data packet isacquired, to be broadcasted to the terminals if the code synchronizationof the data packet is acquired; and a broadcast transmitter forcontrolling the information representing that the code synchronizationof the data packet is acquired, to be broadcasted to the terminals at apredetermined power level in a predetermined time.
 38. The base stationas recited in claim 37, wherein said detection determination meansdetermines the initial code synchronization and the tracking of thesynchronization in a given time before completion of a preambletransmission to make said terminals perform the precise operation in thebeginning of the slot.
 39. The base station as recited in claim 37,wherein said detection determination means searches the codes around thebeginning of each time slot for a duration that may vary from the lengthof the time slot to the length of the preamble.
 40. The base station asrecited in claim 39, wherein said broadcast determination meansdetermines the broadcast signal only with a single bit representing thedetection of the synchronization in the preamble.
 41. The base stationas recited in claim 39, wherein said broadcast transmitter transmits thebroadcast signal determined by said broadcast determination meansthrough an additional channel using a different code other than thepresently used code at every time of completing the slot.
 42. The basestation as defined in claim 39, wherein said broadcast transmittertransmits the broadcast signal determined by said broadcastdetermination means at every time of completing the slot in thepunctured form having the power control bit transmitted through thepilot channel and a time offset.
 43. A method for transmitting a datapacket to a base station in a code division multiple access (CDMA)telecommunication system wherein a plurality of terminals randomlyaccess to a reverse common channel, comprising the steps of: a)receiving state information broadcasted from the base station, the stateinformation representing that a code synchronization of the data packetis acquired in the base station, wherein a code synchronizationdetection is performed based on a preamble of the data packettransmitted from the terminals through the reverse common channel; andb) determining whether the code synchronization of the data packet isacquired or not based on the state information, allowing the terminal totransmit the data packet in the same time slot as the data packet ofwhich the code synchronization is acquired if the code synchronizationof the data packet is acquired, and allowing the terminal to stoptransmission of the data packets if the code synchronization of the datapacket is not acquired.
 44. A method for transmitting a data packet to abase station in a code division multiple access (CDMA) telecommunicationsystem wherein a plurality of terminals randomly access to a reversecommon channel, comprising the steps of: a) at a data generator,generating data packets to be transmitted to the base station; b) at adata transmitter, transmitting the data packets generated in the datagenerator; c) at a terminal RF signal processor, converting the datapackets into a radio frequency (RF) signal and for processing an RFsignal received from the base station; d) at a broadcast signalreceiver, receiving a broadcast signal from said terminal RF signalprocessor, the broadcast signal representing that a code synchronizationof the data packet is acquired in the base station, wherein a codesynchronization detection is performed based on a preamble of the datapacket transmitted from the terminals through the reverse commonchannel; and e) at data transmission determination means, determiningwhether the code synchronization of the data packet is acquired or notbased on the broadcast signal, allowing the data transmitter to continueto transmit the data packet if the code synchronization of the datapacket is acquired, and allowing the data transmitter to stoptransmission of the data packets if the code synchronization of the datapacket is not acquired.
 45. The method as recited in claim 44, whereinthe data packet includes the preamble and user's data, and the power ofthe preamble is set different from that of the user's data.
 46. A methodfor making a plurality of terminals have a random access to a reversecommon channel in a code division multiple access (CDMA) system,comprising: a) at a base station RF signal processor, receiving an RFsignal transmitted from the terminal; b) at a data transceiver,demodulating the RF signal from said base station RF signal processorand generating a data packet to deliver it to an upper hierarchy oranother network or vice versa, generating a signal representing whethera code synchronization of the data packet is acquired or not, c) at adetection determination means, determining whether the data packet isacquired or not upon completing a preamble of the data packet; d) at abroadcast determination means, determining information representing thatthe code synchronization of the data packet is acquired, to bebroadcasted to the terminals if the code synchronization of the datapacket is acquired; and d) at a broadcast transmitter, for controllingthe information representing that the code synchronization of the datapacket is acquired, to be broadcasted to the terminals at apredetermined power level in a predetermined time.
 47. The method asrecited in claim 46, wherein in the step c) the codes are searchedaround the beginning of each time slot for a duration that may vary fromthe length of the time slot to the length of the preamble.
 48. Anapparatus for transmitting a data packet from a first terminal to a basestation in a code division multiple access (CDMA) telecommunicationsystem in which terminals randomly access a reverse common channel, theapparatus comprising: a data transmitter configured to transmit from thefirst terminal a first preamble associated with a first data packetusing a particular time slot of the reverse common channel; a broadcastsignal receiver configured to receive state information broadcast fromthe base station, the state information representing whether a codesynchronization of one or both of the first preamble and a secondpreamble associated with a second data packet and transmitted by asecond terminal in the particular time slot of the reverse commonchannel was acquired in the base station; and a data transmissiondetermination circuit configured to determine whether the codesynchronization of one or both of the first preamble and the secondpreamble was acquired or not based on the state information, and tocause the data transmitter to transmit the first data packet in the sametime slot in which the second terminal transmits the second data packetif the code synchronization of one or both of the first preamble and thesecond preamble was acquired.
 49. The apparatus of claim 48, wherein thedata transmission determination circuit is configured to always causethe data transmitter to transmit the first data packet in the same timeslot in which the second terminal transmits the second data packet ifthe code synchronization of one or both of the first preamble and thesecond preamble was acquired.
 50. The apparatus of claim 48, wherein thedata transmission determination circuit comprises a processor.
 51. Theapparatus of claim 48, wherein the data transmitter is configured totransmit the first preamble at a power level that differs from a powerlevel at which other portions of the first data packet are transmitted.52. A method for transmitting a data packet from a first terminal to abase station in a code division multiple access (CDMA) telecommunicationsystem in which terminals randomly access a reverse common channel, themethod comprising: transmitting, from the first terminal, a firstpreamble associated with a first data packet using a particular timeslot of the reverse common channel; receiving, at the first terminal,state information broadcast from the base station, the state informationrepresenting whether a code synchronization of one or both of the firstpreamble and a second preamble associated with a second data packet andtransmitted by a second terminal in the particular time slot of thereverse common channel was acquired in the base station; and determiningwhether the code synchronization of one or both of the first preambleand the second preamble was acquired or not based on the stateinformation, and transmitting the first data packet in the same timeslot in which the second terminal transmits the second data packet ifthe code synchronization of one or both of the first preamble and thesecond preamble was acquired.
 53. The method of claim 52, furthercomprising always transmitting the first data packet if the codesynchronization of one or both of the first preamble and the secondpreamble was acquired.
 54. The method of claim 52, further comprisingtransmitting the first preamble at a power level that differs from apower level at which other portions of the first data packet aretransmitted.